Reader's Digest caught up with three astronauts to chat about what it's like to live in orbit. Here's what they had to say.

Astronauts aboard the International Space Station witness way more sunrises and sunsets than those of us on Earth: 16 of each per day. That’s because the station travels at about 17,500 miles per hour, completing a full orbit of Earth every 90 minutes.

2. Signs of life on Earth are most visible at night

The most prominent signs of human life during the day are airplane contrails, wakes created by boats, and the textured grey of big cities, says NASA astronaut Terry Virts. But nighttime, he says, is when you really see human activity. “It’s more a vision of wealth than it is of populations,” he says. “Europe shines like a light bulb … whereas Africa is bright around cities like Cairo and Johannesburg, but is otherwise just a few dots of light.”

3. The aurora borealis is stunning from above

“If there was one moment that I framed in my brain as something I never wanted to forget, it was watching the aurora,” says NASA astronaut Kjell N. Lindgren. “It’s not always spectacular, but there are times where you are absolutely floating over a sea of aurora and it’s just undulating rapidly. Your brain can’t comprehend it.”

Photo courtesy NASA

4. Up and down have no absolute meaning

While astronauts aboard the station typically keep their heads toward the overhead and their feet toward the deck, there is no true up or down in space. Labels and light fixtures (which run along the overhead) suggest a certain vertical orientation, but astronauts can switch things up as they want or need to. “Some days I’d [orient myself] with my head toward the deck,” says NASA astronaut Barry “Butch” Wilmore. “Just to do things differently.”

5. Certain foods are MUCH harder to eat in space

In a microgravity environment, where spoons don’t so much hold food as transport it, certain snacks are easier to manage than others. “Rehydrated corn was especially difficult to eat, but it was one of the few vegetable-like foods we had on board that I liked,” says Lindgren. “If you move the spoon too quickly or if someone bumps into you, the corn goes flying everywhere.”

Photo courtesy NASA

6. If you lose something, it could be gone for a while

It’s not uncommon for things to go missing aboard the space station (largely because anything that’s not secure will float away). Virts says that early in one mission, he and his crewmates lost a wrench. Months after it vanished, it reappeared. “For whatever reason, it just floated out from wherever it had been,” he says. “When the station finally comes back to Earth—hopefully decades from now—there will be a lot of lost tools, lights, wedding rings, and who knows what else, re-emerging.”

7. You can see pollution from space

The effect people have on Earth—for good and for ill—is clear. “While I was [aboard the space station], there was a part of Asia where we would always see pollution,” says Lindgren. “And then they had a clean air day where they limited the number of automobiles that could drive into town and those sorts of things. Within days we were able to see a city that we had previously not been able to see.”

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8. Got something in your eye? That’s fairly common

One of the most common physical complaints in space is eye irritation. “Dust doesn’t fall to the ground like it does on Earth” says Lindgren. “It just floats around until our filters filter it out.” Other common ailments include symptoms of allergies and an uncomfortable feeling of fullness in the head. Lindgren says this is because of a net shift of blood to the chest and head due to the lack of gravity. “Your head feels full and looks puffy,” he says.

Photo courtesy NASA

9. Astronauts see the same number of stars as people on Earth

The best view aboard the station is from the seven-window cupola dome. On moonless nights, the planets, stars, aurora borealis, and a spinning Milky Way galaxy are visible. “The view of the stars from space is similar to the experience you’d have if you went to Colorado, climbed a mountain, and didn’t have any lights,” says Virts. “It’s the same number of stars, except we don’t have [to view them through] the atmosphere, which helps.”

10. It’s easy—but uncommon—to play microgravity pranks

Lindgren says that while he never witnessed a space prank firsthand (though there was this gorilla-suit incident), there are a few good ones. “I’ve heard of people falling asleep in the middle of the day in one module, and somebody will come by and move them into a different module,” he says. “So they’ll wake up a bit disoriented.” Lindgren says that because astronauts don’t have to hold themselves up to sit or stand, it’s especially easy for them to accidentally fall asleep.

11. Cargo pants and socks make a good space outfit

It turns out that practical Earth outfits hold up well in space, too. Lindgren says a typical outfit is a cotton T-shirt and pants with lots of pockets and Velcro strips (astronauts use Velcro to keep items secure). “And you don’t need to wear shoes,” he says. “Just socks.”

12. It’s possible to get stuck in place

In order to move from one part of the space station to another, astronauts push off structures—which are almost always reachable—to propel themselves in the direction they need to go. But Virts recalls that after installing the space station’s Node 3 module—and before mounting racks of equipment to its sides—the room was a bit wider than an arm span. “We’d put someone in the middle and they’d just float there,” he says. “After about five or 10 minutes, the air currents would move you enough that you’d be able to grab onto the side.”

13. Saturday movie nights are popular in space, too

While astronauts don’t need to sit down in order to relax and watch a movie (floating in place would work just as well), they tend to do it anyway. “We would all strap ourselves down to the floor with our bungees so that we were sitting or lying back,” says Lindgren, noting that astronaut Scott Kelly was the first to point out the idiosyncrasy. “There’s just something uncomfortable about watching a movie in an upright position.” Unfortunately, they still don’t eat popcorn in space. “That would be a disaster,” he says.

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Photo courtesy NASA

14. Space travel isn’t the only aspect of being an astronaut

Wilmore says one of the biggest misconceptions about an astronaut’s job might be that it’s all about space travel. “Astronauts support NASA’s human spaceflight program. We rarely fly in space,” he says. “I’ve been an astronaut for 15 years and I’ve flown in space twice. And that’s average.”

15. There’s time for hobbies in space

Although astronauts typically work long days from around 7 a.m. to 7 p.m., there is time for reading and hobbies in the evening and on weekends. “I elected to have bagpipes sent up in one of my crew care packages,” says Lindgren.

16. Astronauts have the occasional dream in microgravity

When you spend enough time in a certain environment, you start to dream there, too. “I only had two microgravity dreams while I was in space,” says Lindgren. “And only two since I’ve been back on Earth.” One of his crewmates said about half his dreams aboard the space station were ground-based, while the other half were in microgravity.

17. The work astronauts do on the space station matters to people on Earth

“Space station research affects every discipline of science,” says Virts. “We’re learning how to fix human problems.” Some examples include experiments being done around bone loss, an obstacle astronauts combat in space with rigorous exercise, as well as work being done on combustion efficiency. “If you could change that efficiency by a fraction of a percent, it would be the biggest invention of the 21st century,” says Virts. For more information on the research being done aboard the space station, visit NASA.

Photo courtesy NASA

18. Astronauts often experience an overview effect

When astronauts in space look down on their home planet, they often experience a phenomenon referred to as the overview effect. “We see this amazing, indescribably beautiful planet,” says astronaut Ron Garan in the Planetary Collective film OVERVIEW. “It looks like a living, breathing organism. But it also, at the same time, looks extremely fragile … It really is striking and it’s really sobering to see this paper-thin layer and to realize that that little paper-thin layer is all that protects every living thing on Earth from death, basically. From the harshness of space.”

19. Astronauts often refer to their home planet as Spaceship Earth

Aboard the space station, Lindgren says, astronauts spend an inordinate amount of time doing preventative and corrective maintenance to take care of the vehicle that is taking care of them. “And yet on Earth, which is also a spaceship for all of us, we spend nowhere near the same amount of time taking care of this larger spaceship.”

Photo courtesy NASA

20. “We do not see any borders from space…”

From 250 miles above the planet, world peace seems less a lofty goal and more an urgent priority. “Some things that on Earth we see in the news every day and thus almost tend to accept as a ‘given’, appear very different from our perspective,” wrote German astronaut Alexander Gerst about what he felt as he saw rocket explosions over Israel and the Gaza in 2014. “We do not see any borders from space … From up here it is crystal clear that on Earth we are one humanity … If we ever will be visited by another species from somewhere in the universe, how would we explain to them what they might see as the very first thing when they look at our planet? How would we explain to them the way we humans treat not only each other but also our fragile blue planet, the only home we have? I do not have an answer for that.”